Apparatus for continuous hydrolysis of raffinose

ABSTRACT

An apparatus comprising a U-shaped open reaction vessel which is separated into a plurality of chambers by boundary plates which are so constructed as to allow sugar syrup or juice to overflow through replaceable screen nets fitted at the upper parts of the boundary plates; and said chambers are equipped with an interfering plate and each chamber is equipped with stirrers between the interfering and boundary plates.

I United States Patent [151 3,664,927 Shimizu et al. 5] May 23, 1972 [54] APPARATUS FOR CONTINUOUS HYDROLYSIS OF RAFFINOSE [56] References Cited [72] Inventors; Junichi Shimizu; Toshio Kaga, both of UNITED STATES PATENTS Tokyo, Japan 2,188,192 1/1940 Scholler et a1. ..195/l4l X [73] Assignee: Hokkaido Sugar Company, Ltd., Tokyo,

Japan Primary ExaminerA. Louis Monacell [22] Filed: Sept. 25, 1969 Assistant Examiner-Gary M. Nath [211 Appl- No: 860,876 AttorneySughrue, Rothwell, Mion, Zinn and Macpeak [57] ABSTRACT [30] Forelgn Apphumon Priority An apparatus comprising a U-shaped open reaction vessel Oct. 7, 1968 Japan ..43/72676 which is separated into a plurality of chambers by boundary plates which are so constructed as to allow sugar syrup or juice [52] US. Cl. ..195/141, 195/31 R, 195/ 1 15, to overflow through replaceable screen nets fitted at the upper /2 259/68 parts of the boundary plates; and said chambers are equipped [51] II!!- Cl. ..C12b 1/02 with an interfering plate and each chamber is equipped with [58] Fleld of Search 1 35, 1 15, 139, 140, 141, tir-re s between the interfering and boundary plates,

4 Claims, 2 Drawing Figures Patented May 23, 1972 APPARATUS FOR CONTINUOUS HYDROLYSIS OF RAFFINOSE BRIEF DESCRIPTION OF THE DRAWINGS An apparatus of the present invention and for carrying out the process of the present invention is illustrated in the accompanying drawings.

In the drawings FIG. 1 is a schematic longitudinal sectional views of the reaction vessel.

FIG. 2 is a diagrammatically illustrated process of the present invention.

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a process for continuous hydrolysis of rafiinose and an apparatus therefor. More particularly it relates to a process for continuous hydrolysis of raffinose contained in beet sugar syrup or juice by stirring and contacting the syrup with u-D-galactosidase which is present in the cells of a mold. The mold containing a-D-galactosidase is cultured and shaped in pellet form and the obtained enzyme-agent of pellet form is added in a given amount to each chamber of the reaction vessel fitted with a stirrer as shown in FIG. 1. The beet sugar syrup or juice is contacted with the enzyme-pellets for a required period by passing the syrup through the chambers from one side to another to contact the raffinose with the enzyme for the hydrolysis of raffinose, for promoting the growth of sugar crystals in the crystallization operation of the beet sugar syrup or juice and also for attaining an increased production of sugar.

Hitherto, there is known a method, in which the solution to be reacted is continuously allowed to pass downwardly through a column filled with water-insoluble enzyme combined with the cells of a mold and also another method, in which the solution to be reacted and the similar enzyme-agent as said above are simultaneously brought into a reaction vessel and after the completion of the reaction the enzyme is recovered and used for the process repeatedly.

When examining the above mentioned known methods for hydrolysis of raffinose, it was found to be impossible to apply these methods for large scale production of beet sugar. Thus, when beet sugar syrup of Bx 30 is allowed to pass downwardly through the column at 50 C. which was filled with a-D-galactosidase-enzyme-pellets, the velocity of the current of the sugar syrup gradually falls and the whole enzyme-pellets are compressed into a lump whereby the syrup is channeled and the efficiency of the enzyme extremely decreases. Further, when raffinose-containing sugar syrup of Bx 30 and the above said enzyme-pellet are added in a reaction vessel at the same time and the mixture is reacted at 50 C. for a required period, after the completion of the reaction the enzyme recovered from the reacted sugar syrup is extremely reduced in its activity due to contacting of the enzyme with air during the separation treatment. Furthermore, this process can hardly be practically applied for industrial scale, because the equipment therefor is quite voluminous in size and is also expensive.

In order to overcome the above mentioned disadvantages, we have precisely studied the properties of a-D-galactosidaseenzyme-pellets and the beet sugar syrup or juice containing raffinose as well as the hydrolysis conditions of rafi'mose and found a novel process most suitable for the treatment of beet sugar syrup or juice containing raffinose and an apparatus therefor.

To accomplish the process according to the invention, a mold containing a-D-galactosidase such as Mortierella vinacea variant raffinose utilizer, is cultured in a suitable nutrient culture medium containing lactose to obtain mold of pellet-form having the activity of about 30,000 unit per ml of culture medium. After the isolation of the mold from the cultured broth it can be used as an enzyme-agent and can also be stored in a refrigerator before use.

Beet sugar syrup or juice, which is obtained in each manufacturing process of sugar by extracting sucrose from beet, contains small amount of raffinose, peculiar to the beet sugar syrup or juice and which is a trisaccharide.

In the crystallization of sugar from the beet sugar syrup or juice, raffinose contained therein behaves as a factor to obstruct the growth of sugar crystals. Accordingly, the recovery of sugar can be increased by hydrolyzing of raffinose into sucrose and galactose.

By reacting a-D-galactosidase enzyme-pellets with raw juice, thin juice, middle juice, beet syrup, beet molasses, etc., raffinose contained therein can easily be hydrolyzed equally in each case.

From 60 to percent of raffinose contained in a wide range of between 0.4 and 15 percent based on solid contents in each case of sugar syrup or juice can be hydrolyzed by using l50,000-20,000,000 unit of enzyme per gram of rafiinose and catalyzing for At-1% hours at a temperature of between 30 and 60 C. and adjusting the concentration and pH-value of beet sugar syrup or juice in Bx 10-50 and pH 4.5-7 respectively.

1,500-3 ,000 tons of beet are being treated per day in a beet sugar production plant and the water-soluble substances which are contained in the beet consist mainly of sugar amounts to 300-600 tons and rafi'mose contained in the watersoluble substances amounts to 2-4.5 tons. The process and apparatus for treating such a large amount of sugar syrup or juice with the said enzyme-agent are being quite serious factors in economical consideration.

The apparatus accordingto the invention is equipped with an agitating device as shown in FIGS. 1 and 2 to satisfy the above mentioned reaction conditions of the said enzymeagent.

Since the enzyme-agent according to the invention is porous and is shaped in pellet form when the enzyme-agent is immersed in a sugar syrup or juice the apparent specific gravity of the pellets will be the samewith that of sugar syrup or juice and by mechanical stirring the distribution conditions of the pellets remain always constant without regarding the concentration of sugar syrup or juice if it is in a range of Bx between 10 and 50.

After regulating the concentration and pH-value in aregulating vessel the sugar syrup or juice is allowed to pass through the chambers one after another in one direction by overflow and each overflowing position above the boundary of the two adjacent chambers is fitted with a replaceable screen net of 50-100 mesh. For the sake of adjusting the mesh size of the screen net to a suitable size for the enzyme-pellets which were obtained by culture and which will also be gradually abraded by contacting with sugar syrup or juice during the reaction, the screen nets are so constructed as to be able to be replaced with a net of suitable mesh.

When the activity of the enzyme-pellets decreased by degree by contacting with sugar syrup or juice during the hydrolysis of raffinose, it becomes necessary to supply fresh enzyme-agent, the consumed enzyme can easily be transferred to the next chamber by removing the screen net and thus the activity of the enzyme-agent in the chambers can be controlled and kept constant.

The reaction vessel may have any number of chambers, such as three or more.

The hydrolysis of raffinose according to the invention has the following advantages, in detail:

1. As the hydrolysis of raffinose contained in beet sugar syrup or juice according to the invention can be carried out continuously, it is suitable for industrial large scale treatment.

2. Since the reaction can be carried out continuously, it is quite efficient and large amount of beet sugar syrup or juice can be treated by using relatively small apparatus.

3. Since contact of the syrup or juice with air is small, deactivation of the enzyme caused by aerial oxidation can be avoided.

4. Regulation of the activity of the enzyme-agent is easy and control of the reaction is simple.

5. A large amount of enzyme-agent may be added freely in any chamber of the reaction vessel and so the reaction period can be reduced.

6. By using a beet sugar syrup or juice of high concentration autolysis of the enzyme can be prevented.

As mentioned above, the present invention has technically and economically attained remarkable progress in the hydrolysis of raffinose contained in beet sugar syrup or juice.

EXAMPLE A. Apparatus A longitudinal side sectional view of the reaction vessel is shown in FIG. 1.

A stainless steel-reaction vessel 2 fitted with jacket 1 is divided in three chambers and is equipped with a shaft of the agitator 3 passing through the central part of each chamber. Above each boundary plate 4 there is fitted a replaceable screen net 5 of mesh size between 60 and 80. In order to regulate the stream of sugar syrup or juice there is provided an interrupting plate 6 in each chamber and the lower part of which is opened to allow passing through of syrup or juice. Blades are fitted to the shaft of the agitator at the middle of each chamber and also at the middle of the space between each boundary plate and interrupting plate and their lengths are so in the second and third chambers somewhat increase. When sugar syrup has been passed through the reaction vessel for 4 days, percent of the enzyme-pellets used is consumed.

At this time the screen net of the first chamber is removed and the remaining enzyme therein is transferred to the second and third chambers and 50 percent of the enzyme-pellets corresponding to the consumed pellets are charged in the first chamber and the screen net of 60 mesh is placed at the first chamber and those of 80 mesh are placed at the second and third chambers. The same sugar syrup as said above has been passed through the reaction vessel.

C. Results The composition of beet molasses used is shown, as follows:

Solid content 85% Sucrose 65%/Bx Reducing sugar 0.5/Bx Raffinose 4%/Bx Ash 5%/Bx Color (Stammer Color Value) 230 TABLE I Hydrolyzed sugar syrup Reaction conditions Rate of Time hydrolysis Flow out Temper- Supplying Time reacted of raflinose volume of ature rate of Day operated (11.) (percent) syrup (1.) C.) (l./h.) 1st {First half 12. 0 87 35. 0 48-50 2. 91 Second hall. 12. 0 82 35.0 48-50 2.01 ml {First half 12.0 80 35. 0 45l-50 2.!)1 ")Sucond half. 12. 0 X1 36. 0 48-50 2.01 3rd {First llztll' 12. 0 81 35. 40-5O 3. .11 Svcond lmlL 12. 0 80 35.0 47i-50 .01 4m {First llnlf 12. 0 78 35.0 40-50 .3. 01 Second lmlL 11.0 76 32.0 -i0-50 K01 Sum 05. 0 277. 0

adjusted as to extend the ends to the surface of the liquid. This is important for preventing the choking of the screen nets placed above the boundary plates with enzyme-pellets and the choking is closely influenced by the revolution of the agitator. Accordingly variable driving means 7 is used for the agitator. At the end of the last chamber there is fitted a leveling pipe 8.

B. Operation The operation is also illustrated in the accompanying draw ing (FIGS. 1 and 2).

Referring now to the drawing beet sugar molasses or syrup is introduced in the diluting and regulating vessel 3 (ref. FIG. 2) and is diluted with warm water 2 up to Bx 30 and then the pI-l-value is adjusted with sulfuric acid to 5.2. The treated sugar syrup is supplied in the reaction vessel having substantial contents of 3.81 4 continuously in a rate of about 2.8-2.91 per hour. 700 g of the enzyme-pellets are charged in the chambers so as to place an equal amount of enzyme-pellets in each chamber and the revolution of the agitator is adjusted to 120 rpm. and the screen net of 60 mesh is fitted above theboundary plate of each chamber and water of C. is circulated in the jacket to maintain the temperature of sugar syrup at 4850 C. constantly. The leveling pipe is so adjusted as to control the retention time of sugar syrup in the reaction vessel for one-fourth hour.

In this manner sugar syrup of Bx 30 is passed continuously through the reaction vessel for 4 days.

During this course the size of enzyme-pellets becomes smaller as they abraded and the qualities of the enzyme-agent The enzyme shaped in a pellet form to be used is obtained by culturing Mortierella vinacea variant rafi'inose utilizer under in a culture medium mainly containing lactose in aerating and stirring conditions, centrifuging the deposited mold of pellet-form followed by refrigerating and then remelting to dissolve out water soluble substances and again centrifuging to obtain enzyme-pellets containing 67 percent of water and having the activity of 600,000 unit per gram. After the completion of the test (the first half test for four days) the total activity of the enzyme decreased to 48.6 percent of the initial activity, whereas the activity of the enzyme based on solid is observed to be constant. The decrease of the total activity of the enzyme to 48.6 percent of the initial activity is mainly due to the abrasion of 5 1.4 percent by weight of the solid part of the enzyme-agent.

A molasses having the above mentioned composition and at the same time a molasses in which percent of raffinose contained therein is hydrodysed are both treated as usually with a boiling operation. By comparing microscopic photographies of the both crystals obtained therefrom definite differences are observed between these two as shown in FIG. 3.

In the 4 days second half test according to the invention 76-85 percent of raffinose contained in the syrup can be hydrolysed as shown in Table II.

In this manner about 80 percent of raftinose contained in the sugar syrup can be hydrolysed and it is found that 70,000-80,000 units of the enzyme are required for the hydrolysis of l g of rafiinose.

TABLE II Hydrolyzed sugar syrup Reaction conditions Rate of Time hydrolysis Flow out Temper- Supplying Time reacted of rafiinose volume of ature rate of Day operated (h.) (percent) syrup (1.) C.) (1.]11.)

th {First half 12.0 85 35.0 48-50 2. 91 Second half. 12.0 83 35.0 49-50 2.91 am {First half. 12. 0 84 35. 0 50-50 2. 91 Second half. 12.0 80 35.0 49-50 2.91 7th {First hali 12. 0 78 35. 0 48-50 2. 91 Second half. 12.0 79 35. 0 49-50 2. 91 8th First half... 12.0 78 35.0 48-50 2. 91 Second halL 8.0 76 23.3 49-50 2.91

Sum 92.0 268. 3

What is C m d is: plate and each boundary plate and driving means for said stir- I. An apparatus for continuously hydrolyzing raffinose conrers. tained in beet sugar syrup comprising a U-shaped open reac- 2. An apparatus according to claim 1, wherein said vessel is tion vessel having a plurality of boundary plates therein to divided into at least three chambers. define a plurality of chambers, said boundary plates being so 3. An apparatus according to claim I wherein the mesh size constructed as to allow the sugar syrup to flow thereover from of said screen nets is less than 100. one chamber to another, a replaceable screen net secured at 4. An apparatus according to claim 1 wherein the revolution the upper edge of each boundary plate, an interfering plate Ofthe driving m n r h l fl' r n be rie disposed in each chamber to regulate the current of the syrup, k w stirrers disposed in each chamber between each interfering 

2. An apparatus according to claim 1, wherein said vessel is divided into at least three chambers.
 3. An apparatus according to claim 1 wherein the mesh size of said screen nets is less than
 100. 4. An apparatus according to claim 1 wherein the revolution of the driving means for the stirrers can be varied. 